1. Technical Field
The present invention generally relates to semiconductor devices and methods of fabricating semiconductor devices. More particularly, the present invention relates to preventing damage to silicide in transistor fabrication during non-self-aligned contact metallization.
2. Background Information
Silicide processes have been widely used to form silicide contacts on gate regions and source/drain regions during the semiconductor device fabrication processing to improve the performance of the semiconductor device. The silicide layer improves the operational speed of the semiconductor device by reducing the contact resistance between the metal contact and the source, drain and gate regions.
In a typical semiconductor fabrication processing, one or more etching processes are performed simultaneously using a photoresist mask, to selectively form contacts over the silicide in source, drain and gate regions of the semiconductor device. The photoresist mask is subsequently removed by employing dry chemistries involving reactive oxygen, such as oxygen plasma. The use of oxygen plasma results in the formation of polymeric etch residues at the bottom of contact openings in source, drain and gate regions of the semiconductor device. After the oxygen plasma ash is performed, the polymeric etch residues are removed by employing prior art processes to treat the exposed silicide. However, the oxygen plasma ash processes and other prior art processes cause damage to the exposed silicide and increase the resistance of the subsequent contact metallization, resulting in degradation of the performance of the semiconductor device.
Hence, there exists a need to prevent damage to silicide during contact metallization and improve the performance of semiconductor device.